A known door lock device includes a latch mechanism provided at a vehicle door and engageable with or disengageable from a striker provided at a vehicle-body, a lift lever for operating the latch mechanism from an engaged state to a disengaged state by engaging with or disengaging from the striker, an open lever operated by an operation of a door opening member provided at the vehicle door, and a lock lever provided at the vehicle door and movable between an unlocked position and a locked position by an operation of a door locking/unlocking member. The known door lock device further includes an open member operated with the lock lever and movable between the unlocked position and the locked position. When the open member is in the unlocked position, the open member engages with the lift lever by the operation of the open lever in one direction, thereby allowing the lift lever operable. When the open member is in the locked position, the open member idly engages with the lift lever by the operation of the open lever and then becomes engaged with the lift lever in the other direction, thereby prohibiting the lift lever operable when the open member is switched to the unlocked position from the locked position.
According to the known device, an unlocked state is defined when the open member is in the unlocked position while a locked state is defined when the open member is in the locked position. In the unlocked state, the open member is operated with the lift lever by engaging therewith due to the operation of a door handle and the like whereby the latch mechanism disengages from the striker. In the locked state, the open member idly engages with the lift lever and thus the lift lever is not operated even if the door handle is operated. The latch mechanism cannot disengage from the striker accordingly.
When the door handle and the door locking/unlocking member such as a door lock knob are operated at substantially the same time in the locked state, the aforementioned device is known to cause a problem as follows. When the door handle is operated before the operation of the door lock knob, the open member idly engages with the lift lever and then moved to a direction of the unlocked position. In this case, the open member engages with the lift lever in the other direction and thus both the lock lever and the open member cannot be moved to the unlocked position. Thus, when the door handle is returned to a normal position from a pulled position, the door lock knob remains in the locked position even though the door lock knob is once operated to be unlocked (which is called a panic state). It is required to operate the door lock knob again to switch to the unlocked state, which causes the bother of operation. This kind of bother may occur in a door lock system for automatically switching to the unlocked state from the locked state by detecting an approach of the user's hand to the door handle. The door handle can be operated before the automatic switching to the unlocked state is performed depending on control timing.
A device disclosed in Japanese Patent Laid-Open Publication No. 11-166337 is known to solve the above-mentioned problem. FIG. 17 shows a structure of the disclosed device. The disclosed device includes a lift lever 100 for operating the latch mechanism from the engaged state to the disengaged state by engaging with or disengaging from the striker provided at the vehicle body, an open lever 101 operated by the operation of the door handle provided at the vehicle door, and a lock lever 102 provided at the vehicle door and operated by the operation of the door lock knob and the like. The disclosed device further includes an open link 103 operated with the lock lever 102 and movable between the unlocked position and the locked position. The open link 103 engages with the lift lever 100 in S direction, thereby allowing the lift lever 100 operable when the open link 103 is in the unlocked position. The open link 103 also idly engages with the lift lever 100 in the locked position. The open link 103 includes a main link 103a connected to the open lever 101 and the lock lever 102, and a sub link 103b mounted on the main link 103a via a pin 104 so that the sub link 103b relatively rotates to the main link 103a and engageable with the lift lever 100. FIG. 17 shows the locked state in which the sub link 103b does not engage with the lift lever 100.
The aforementioned disclosed device is operated as follows in the locked state when the door handle and the door lock knob are operated substantially at the same time. The open link 103 is moved in substantially S direction while idly engaging with the lift lever 100 by the operation of the door handle. Then, the open link 103 is moved in T direction, i.e. unlocked position, by the operation of the door lock knob. In this case, the sub link 103b engages with the lift lever 100 and relatively rotates to the main link 103a. The main link 103a of the open link 103 is therefore moved to the unlocked position together with the lock lever 102. When the door handle is returned to the normal position, the sub link 103b relatively rotates to the main link 103a by a biasing force of a spring 105. Then, the open link 103 as a whole is returned to the unlocked initial position (i.e. recovered from the panic state). It is thus not required to operate the door lock knob again.
The above-mentioned device, however, may have a following problem. The open lever 101 and the main link 103a receive torque generated by the operation of the door handle under the door opening operation with the door unlocked. The sub link 103b is moved in substantially longitudinal direction thereof (lower-left direction in FIG. 17) by the main link 103a. The lift lever 100 is pushed by an edge portion of the sub link 103b. The main link 103a and the sub link 103b are rotatably connected via the pin 104 as mentioned above. Therefore, the sub link 103b may not be stably supported relative to the main link 103a when the sub link 103b pushes the lift lever 100, That is, the sub link 103b and the main link 103a may relatively rotate to each other and thus the lift lever 100 cannot be accurately pushed. The relative rotation between the sub link 103b and the main link 103a is restricted by the spring 105. However, if a relative relationship between the biasing force of the spring 105 and torque required for operating the lift lever 100 is changed, the above-mentioned problem may occur and thus operation instability of the door lock device may be caused.
Thus, a need exists for a door lock device which addresses at least the foregoing drawback associated with other known door lock devices.
It would thus be desirable to provide a door lock device which can provide the operation stability and reduce the bother of operation.